Gut associated microbiome is an essential component of the mammalian body. The composition of the microbial inhabiting the gut play important role in the absorption of nutrients from the food and the associated metabolic activities. Body composition as well as energetics are critically regulated by the the dynamics between the gut associated microbial components and the mammalian body. Recent studies have indicated a strong association between the microbial families that inhabit the gut and the composition of the intestinal immune systems. In fact specific immune cells have been associated with the retention of bacterial families that control mammalian well being. The goal of this study is to evaluate age-dependent changes in the composition of immune cells and microbiome in mice that age in a controlled environment with steady diet and no interruption in well being.